Philosophy of Religion is the study of
the meaning and justification of fundamental
religious claims, particularly about the
nature and existence of God (or gods, or
the divine).
Philosophy of religion was
classically regarded as part of metaphysics, since
Aristotle, in some of whose writings were... ...

Theology was used as early as in Plato's Republic (book ii, chap
18). The the term, compounded from two Greek
words theos (god) and logos (rational
utterance), has been defined as reasoned discourse about God or
the gods, or more generally
about religion or spirituality. ...

Gnosticism is a blanket term for various
religions and sects most prominent in the
first few centuries A.D. Many elements of
second-century gnosticsm are pre-Christian.
The name of gnosticism comes from the Greek word for
knowledge, gnosis (??????), referring
to the idea that there is special, hidden
knowledge (esoteric knowledge) that
only a few may possess. ...